Asymmetric Synthesis of All Possible Stereomers of 4‐Aminoglutamic Acid via Michael Condensation of Chiral Ni(II) Complexes of Glycine and Dehydroalanine

Abstract

A new method for asymmetric synthesis of all possible stereomers of 4‐aminoglutamic acid has been developed. The method is based on asymmetric Michael condensation of the nucleophilic moiety of glycine and electrophilic moiety of dehydroalanine in their chiral Ni(II) complexes of the Schiff's bases with (S)‐ and (R)‐2‐N‐(N′‐benzylprolyl)aminobenzophenones, resulting in the formation of dimeric complexes of 4‐aminoglutamic acid. Stereoselectivity of the asymmetric condensation of the complexes exceeded 94%. The condensation of nucleophilic and electrophilic complexes in four possible combinations has resulted in the formation of dimeric complexes of all the stereomers of 4‐aminoglutamic acid: (2S,4S), (2S,4R)‐meso and (2R,4R). Optically active stereomers of 4‐aminoglutamic acid with high optical purity were isolated after decomposition of the dimeric complexes.

Keywords:

• 4‐Aminoglutamic acid
• asymmetric synthesis
• chiral Ni(II) complex
• dehydroalanine
• stereomer
• stereoselectivity

Acknowledgments

The research reported herein was supported by International Science and Technology Center (ISTC) grants (Projects A‐1247 and 2780).